Abstract

This study evaluates the effects of remediation of gas flared soil by biochar on the nutritional composition of cultivated Telfairia occidentalis leaves, relative to non-gas flared soil. Gas flared soils are degraded due to the presence of heavy metals, noxious gases, carbon soot and acidic rain. Biochar produced from oil palm fibre was applied at five different amounts: 0 t ha−1, 7.1 t ha−1, 13.9 t ha−1, 20.9 t ha−1 and 28.0 t ha−1 to containerized soils (both gas flared and control soil), inside a greenhouse, which were allowed to mineralize for two weeks. Two viable seeds of T. occidentalis per replicate were sown. After eight weeks of growth, leaves were harvested, dried and chemically analyzed. Application of biochar significantly increased leaf ash and crude fibre content of Telfairia occidentalis. Plants from soil treated with 13.9 t ha−1 of biochar had the highest concentrations of vitamins A, B1, B2, B6, C and E irrespective of soil type. Maximum increase in leaf vitamin and mineral content was obtained from leaves cultivated on gas flared soil treated with 13.9 t ha−1 and 7.1 t ha−1 of biochar respectively. The results show that biochar treatment can increase leaf mineral concentrations and that this effect is dependent on the amount of biochar application.